ABSTRACT The reliable integration of superconducting alloys with dielectric substrates is a challenge in the fabrication of advanced cryogenic devices. In this study, a novel Sn‐Bi‐In‐Ga‐Zn quinary solder doped with amino‐functionalized carbon quantum dots (N‐CQDs) was developed to realize the robust joining of Niobium‐Titanium (NbTi) alloy and fused quartz. The impact of N‐CQDs on the interfacial microstructure, mechanical integrity, and superconducting properties was investigated. Results demonstrate N‐CQDs act as “dual‐functional bridges” at the hetero‐interface. The shear strength of the N‐CQD doped joint reached 51.5 MPa at room temperature, a 51.3% enhancement over the untreated joint. This strengthening is attributed to the formation of a covalent siloxane anchoring network (Si─O─Si) on the quartz side and strong amino‐metal coordination on the metallic side, per XPS and FTIR analyses. Furthermore, the self‐field critical current density (Jc) of the joint at 4.2 K was improved by ∼33.3% to 6.4 × 10 5 A/cm −2 . First‐principles density functional theory calculations reveal that amino functionalization significantly increases the interfacial binding energy and enhances the electronic density of states near the Fermi level. Together with the low‐temperature V – I measurements showing a reduced apparent joint/interface resistance, these results suggest improved interfacial electronic coupling and superconducting transport across the joint.

Laser powder bed fusion (LPBF) of metastable β-Ti alloys commonly produces epitaxial columnar β grains and heterogeneous residual strain. Post-build heat treatments can coarsen the rapid-solidification substructures retained in the as-built state. A Ti–11Nb–6Zr–2Fe–2Mo alloy was designed using the Bo–Md approach near the β+ω phase-stability boundary. The as-built alloy retained a metastable body-centred cubic (BCC) β matrix containing nanoscale ω precipitates. Continuous-meander, stripe, and checkerboard scanning were compared at P = 290 W and v = 800 mm/s. Two-dimensional EBSD showed finer, less elongated, equiaxed-like β grains after checkerboard scanning, indicating disrupted continuous epitaxial growth. Checkerboard specimens also had the lowest EBSD-inferred local geometrically necessary dislocation (GND) density in the sampled regions. TEM revealed scan-strategy-dependent differences in nanoscale ω precipitates within the observed fields of view. The checkerboard-processed alloy reached an ultimate tensile strength of 1199 ± 12.3 MPa and an elongation of 13.21 ± 2.4%. Within the tested conditions, phase-stability design and scan-path control improved the strength–ductility balance without post-build heat treatment.

To improve the mechanical properties of aluminum alloy and steel joints and suppress the excessive formation of brittle intermetallic compounds (IMCs) at the interface during laser welding, AlSiCu alloy powder and composite powder prepared by AlSiCu + Mo powder were employed as an interlayer for deep penetration welding with laser lap of 6016 aluminum alloy and DC06 low-carbon steel, respectively. The results indicate that with the process parameter conditions of laser power of 900 W, welding speed of 0.07 m/s, and defocus distance of +2 mm, after adding either AlSiCu powder or AlSiCu + Mo composite powder to the interlayer, the welding process is stable, and the weld formation is sound. Both the penetration depth and weld width on the aluminum side increase compared with those obtained without powder. Moreover, with the addition of AlSiCu + 3% Mo composite powder, the grain structure is refined; brittle Fe-Al IMCs are reduced, and the sizes of layered and acicular phases at the interface are decreased. The tensile-shear force of the aluminum/steel welded joint reaches 82.3 N/mm, which is 25.3% higher than that of the joint without powder addition, and the fracture occurs in the heat-affected zone of the aluminum alloy and part of the aluminum base metal.

A novel, high strength, low modulus, and ductile metastable ,B Ti-14Nb-6Zr-3Fe (TNZF) alloy was manufactured via laser powder bed fusion (LPBF) in-situ alloying. Process parameter optimization resulted in near-fully dense samples ( < 0.1% porosity) under optimal conditions. The microstructure and mechanical properties of TNZF alloy were then tailored using two chessboard scanning strategies and a simple scanning strategy. Samples fabricated using the chessboard scanning strategy (CS-TNZF) benefited from a lower thermal gradient, the high growth restriction factor associated with the addition of Fe, and constitutional supercooling around residual Nb particles, resulting in a near-equiaxed grain structure (average aspect ratio: 2.0) compared to the AS-TNZF (fabricated using the simple scanning strategy). The microstructure consisted of a ,B-Ti matrix with 2-5 nm sized w precipitates. Due to the addition of Zr, the transition from ,B to w was suppressed during thermal cycling associated with LPBF, resulting in the presence of a partially collapsed w phase. Without post-processing heat treatments, the AS-TNZF condition exhibited a yield strength (YS) of 1091 MPa, an elastic modulus (E) of 68 GPa, and an elongation (EL) of 16.8%, while the CS-TNZF counterpart achieved a higher YS of 1147 MPa and E of 71 GPa, but a lower EL of 10.8% due to a higher volume fraction of w phase. Both AS-TNZF and CS-TNZF demonstrated high elastic admissible strain values (YS/E ratio) of 1.60 and 1.62, respectively, achieving high strength, low modulus, and good ductility, which indicates their suitability for biomedical implant materials. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Achieving high strength, low elastic modulus, and excellent ductility simultaneously remains a challenge for additively manufactured biomedical beta titanium alloys. In this work, a novel Ti-14Nb-6Zr-3Fe-3Sn-0.65O metastable beta titanium alloy was developed. By tuning solid solution and precipitation strengthening through Sn and O additions, the alloy achieves an outstanding combination of yield strength (1217 MPa), elastic modulus (67 GPa), and elongation (13%). The addition of Sn effectively refines the grain size and suppresses the precipitation of the w phase, while also mitigating the effect of O on w phase formation. The high strength originates from both solid solution strengthening (561 MPa) and precipitation strengthening (268 MPa). EBSD and TEM results reveal that the synergistic operation of multiple slip systems, frequent cross-slip, and effective slip transfer across grain boundaries are responsible for the alloy's excellent ductility. This work demonstrates that controlling the relative contributions of solid solution and precipitation strengthening offers a promising strategy for designing high performance beta titanium alloys.

In order to elucidate the wetting spreading mechanism, kinetic properties and their influencing factors of the AgCuNi/Ti system on an atomic scale, the present study systematically investigates the wetting behaviour of the system at different temperatures and nickel (Ni) contents through molecular dynamics simulations. The study focuses on analysing the influence of interfacial element diffusion and phase structure changes on the wetting process. The results show that in the (Ag72Cu28)xNiy/Ti system, the Cu atoms in the droplet react with the Ti atoms in the substrate in a significant solvation reaction, forming Cu-Ti compounds with body-centred cubic (BCC) structure and Ag solid solutions with face-centred cubic (FCC) structure. With the increase of Ni content in the droplets, the Cu-Ti reaction became more significant, leading to the formation of more BCC Cu-Ti compounds and promoting the generation of FCC Ag solid solutions.The increase of Ni content not only intensified the chemical reaction between Cu-Ti, but also significantly affected the kinetic properties of the whole wetting process. In addition, it was found that the temperature also had an important effect on the wetting behaviour, with higher temperatures resulting in faster Cu-Ti reaction rates and better wetting effects.

Developing titanium alloys with high elastic admissible strain (EAS) is crucial for biomedical applications. In this study, a series of Ti-14Nb-6Zr-3Fe-xO (TNZF-xO, x = 0.20, 0.35, 0.50, 0.65 wt%) metastable (3 titanium alloys were fabricated via laser powder bed fusion to investigate the role of oxygen in tailoring microstructure and resulting mechanical properties. Microstructural analysis revealed that oxygen addition induced spinodal decomposition of the (3 matrix into (3 ' phases and promoted the precipitation of the w phase. A slight refinement in grain size, from 30.5 & micro;m to 28.1 & micro;m, was observed with increasing oxygen content. Mechanical testing demonstrated that higher oxygen levels led to a continuous increase in yield strength (from 1147 MPa to 1288 MPa) and hardness (from 4.06 GPa to 4.58 GPa). This strengthening is primarily attributed to the w phase and solid solution strengthening, while the (3 ' phase contributes to work hardening during deformation. The elastic modulus exhibited a non-monotonic trend, initially decreasing and then increasing, which is attributed to the competing effects of (3-phase destabilization and w-phase stiffening. The TNZF-0.65O alloy demonstrated a yield strength of 1288 MPa, an elastic modulus of 70 GPa, an elongation of 5.6%, and an exceptional EAS of 1.84.

Purpose This study aims to optimize the electrohydrodynamic (EHD) inkjet printing process for silver nanoparticle ink on alumina (Al2O3) ceramic substrates, focusing on improving print quality and reducing the electrical resistance of silver circuits. Design/methodology/approach This study systematically examines the influence of key process parameters (amplitude voltage, bias voltage, pulse frequency and duty cycle) on silver circuit printing quality, establishes a coupled electric field-hydrodynamics model via COMSOL Multiphysics to analyze the correlation between electric field distribution and droplet ejection, explores the effect of 160-200 degrees C sintering temperature on silver layer densification and controls the number of printed layers to test electrical performance. Findings The optimal process parameter combination for the EHD inkjet printing process is determined as bias voltage 800V, amplitude voltage 1200V, pulse frequency 100 Hz and duty cycle 30%; the coupled electric field-hydrodynamics model established by COMSOL Multiphysics reveals the correlation mechanism between electric field distribution and droplet ejection behavior, thereby theoretically validating the rationality of the parameter optimization; eight-layer unsintered nanosilver printed lines sintered at 200 degrees C exhibit a low resistance of 2.7O across a 20 mm length. Originality/value This study provides a parameter optimization scheme for the EHD inkjet printing of silver nanoparticle ink on alumina ceramic substrates; it establishes a coupled electric field-hydrodynamics model to support the optimization of the EHD inkjet printing process theoretically; it clarifies the effects of sintering temperature and the number of printed layers on the electrical performance of the silver circuit.

Understanding the mechanism of phase transformation and porous formation is crucial for regulating and controlling the in-situ reaction formation of porous structures. In this work, wet chemical method was combined with vacuum heat treatment technique to form porous structure on the surface of Ti coated with a thin layer of Ag. The temperature dependence of phase formation and pore morphology evolution during the porous formation process was investigated. The results indicate that the mechanical bonding between Ti substrate and Ag coating undergoes Ti-Ag mutual diffusion and Ag sublimation, transitioning from layered Ti2Ag and TiAg layers to embedded forms, ultimately forming pores as the temperature increases. This is attributed to the residual beta-Ti on the upper surface undergoes eutectoid reaction with TiAg to generate Ti2Ag, exhibiting the morphology of TiAg embedded in the Ti2Ag layer. And the reverse reaction of peritectic reaction occurs to form L(Ag, Ti). The continuous sublimation of Ag promotes the formation of uniformly distributed micro-pores (5 mu m). Furthermore, porous Ti exhibits excellent corrosion resistance performance compared to other porous metals and an elastic modulus (60.2 GPa) similar to that of human bone.

A surface Ni/Cu coating was applied to the TiC-Ni cermet using the resistive evaporation method. Subsequently, the coated cermet was joined to itself by vacuum brazing using the Ag-Cu28 brazing alloy. The study investigated the formation mechanism of the joints and the impacts of heating temperature and holding time on the joint’s interfacial microstructure and mechanical properties. The results showed that during the heat treatment, the atoms within the Ni/Cu coating interdiffused, forming a continuous (Cu, Ni) layer adjacent to the cermet interface, which could promote the wettability of the liquid alloy and increase the shear strength of joints. The typical microstructure of the joints was TiC-Ni/(Cu, Ni)/Ag(s,s) + Cu(s,s)/(Cu, Ni)/TiC-Ni. Meanwhile, the joint shear strength achieved a maximum value of 146 MPa with a heating temperature of 800 °C for 10 min. And the joint fracture occurred in the interfacial region between the base material and the (Cu, Ni) reaction layer. The reaction layer became discontinuous with an increase in temperature or time. With increasing temperature, the shear strength tended to increase first and then decrease. With the extension of time, the shear strength gradually decreased.

To address the problems of stress shielding and premature implant failure in orthopedic applications, this study presents a surface-porous Ti-Nb-Ag alloy with a bone-matching elastic modulus, fabricated via Ag hightemperature diffusion and vacuum removal strategy. The fabrication process involved electroplating Ag onto Ti-xNb (x = 0, 10, 50 wt%) substrates, followed by high-temperature vacuum heat treatment (1100 degrees C and 5 x10- 4 Pa) to engineer porous surface. The porous Ti-Nb-Ag structure forms through Ag sublimation, a peritectic reverse reaction, and Ti phase reorganization under high-temperature vacuum conditions. As a beta-phase stabilizing element, Nb inhibits the grain boundary diffusion of Ag by changing its segregation behavior at different temperatures. The local elastic modulus of the surface pores on the Ti-10Nb-Ag alloy is 43.4 +/- 2.3 GPa, primarily attributed to its high porosity (41 % porosity, average pore size of 3.62 mu m). The electrochemical measurements in simulated body fluid (SBF) revealed that the porous Ti-10Nb-Ag exhibited a corrosion rate (Icorr = 41.71 mu A/cm2) higher than that of dense Ti (Icorr = 1.38 mu A/cm2), primarily due to the enhanced cathodic activity from residual Ag. Furthermore, after 7 d of culture, MG-63 cell viability remained above 80 %, indicating that the porous Ti-10Nb-Ag exhibits excellent biocompatibility. And achieved 100 % antibacterial efficacy against Staphylococcus aureus(S. aureus) within 48 h via sustained Ag+ release. These findings underscore the surface-porous Ti-Nb-Ag alloys exhibit potential applications in biomedicine.

Laser powder bed fusion (LPBF) additive manufacturing offers significant potential for the cost-effective production of Ti alloy components using ball-milled hydrogenation-dehydrogenation (HDH-Ti) powder. However, ball milling generates morphologically diverse powders-including irregular, near-spherical, and flake-like particles accompanied by fine debris-resulting in broad size distributions that compromise powder spreading homogeneity. To address this challenge, this study integrated discrete element method (DEM) simulations with laser process optimization. A validated DEM model, incorporating statistically characterized particle morphologies (12 types, >15 mu m), revealed critical spreading thresholds: layer thicknesses below 75 mu m induced arching defects, whereas scraper speeds exceeding 50 mm/s reduced packing density through shear dilation and inertial effects. Subsequent LPBF parameter screening identified a laser power of 250 W and a scan speed of 800 mm/s as optimal, achieving a relative density of 99.25 %. Remelting further increased the density beyond 99 % and delivered exceptional mechanical properties, including an ultimate tensile strength of 984 MPa and an elongation of 29 %. Microstructural analysis confirmed fine alpha '-martensite grains (6.4-6.6 mu m) and dense dislocation networks, while oxygen solute strengthening and heterogeneous nucleation contributed to the superior strength-ductility synergy.

To obtain high quality brazed joint of diamond and kovar alloy, systematic work was conducted. Firstly, AgCuTi filler alloy was used for vacuum brazing of diamond to kovar alloy, and the microstructure of resulting joints was systematically characterized to elucidate the formation mechanism. Then, the effects of brazing temperature on joint microstructure and shear strength were investigated, and the correlation between microstructural evolution and shear strength was established. The results indicate that the AgCuTi filler alloy exhibits excellent wettability on the diamond substrate, with a contact angle (theta) of 2.7 degrees. The microstructure characteristics of the diamond/ kovar brazed joint are diamond/TiC+Ag(s, s) + Cu(s, s) + Fe2Ti + Ni3Ti/kovar. A maximum shear strength of 100.94 MPa is obtained at 870 degrees C with a holding time of 5 min. With increasing brazing temperature, the (Fe, Ni) Ti reaction layer thickens, the banded structure of brittle intermetallic compounds (IMCs) Fe2Ti and Ni3Ti broadens. This microstructural evolution initially enhances the shear strength but eventually leads to a decline due to excessive IMCs formation.

The development of novel titanium implant materials with enhanced wear and corrosion resistance and a low elastic modulus is fundamental nowadays. In this work, the microstructure, wear resistance, corrosion behavior, and biocompatibility of Ti-14Nb-6Zr-3Fe (wt

In a high vacuum environment, the wetting and spreading characteristics of Al-Si eutectic brazing filler metal on the surface of pure Fe substrate were tested respectively when the maximum holding temperature was 970 K, 1000 K, and 1030 K. The Fe element in the substrate diffuses into the Al-Si brazing alloy. The Si element in the brazing alloy also diffuses into the substrate, while the Al element does not deeply diffuse into the substrate. The wetting and spreading process was calculated by using the method of molecular dynamics simulation. In order to match the Al-Si/Fe system, an improved modified embedded atom method (MEAM) potential was proposed. Utilizing the improved MEAM potential, the influence of different crystal grain orientations of Fe substrate and the presence of Si element on the wetting mechanism of aluminum-based brazing filler metal were elucidated, emphasizing elements diffusion and reaction during wetting. Simulation results indicate that pure Al and Al12.2Si show similar wetting processes, achieving the minimum wetting contact angle on the Fe (111) crystal plane. The movement process of the molten droplet atoms can be divided into three stages: rapid contact, slow diffusion, and gradual stabilization, and this phenomenon matches the experimental results.

Purpose - This paper aims to conduct work to obtain high-quality brazed joint of YAG ceramic and kovar alloy. Design/methodology/approach - Wetting and spreading behavior of AgCuTi fi ller alloy on YAG ceramic and kovar alloy under vacuum (2 similar to 3 x 10(-4) Pa) and argon conditions was investigated and compared. Then, YAG ceramic was brazed to kovar alloy under a high vacuum of 2 similar to 3 x 10(-4) Pa; the influence of holding time on the interface structure of the joint was investigated. Findings - The wettability of AgCuTi on YAG is poor in the argon atmosphere, the high oxygen content in the reaction layer hinders the formation of the TiY2O5 reaction layer, thereby impeding the wetting of AgCuTi on YAG; in the vacuum, a contact angle (?=16.6 degrees) is obtained by wetting AgCuTi fi ller alloy on the YAG substrate; the microstructure of the YAG/AgCuTi/kovar brazed joint is characterized to be YAG/Y2O3/(Fe, Ni)Ti/Ag(s, s) + Cu(s, s)/Fe2Ti + Ni3Ti/Fe2Ti/kovar; at 870 degrees C for the holding time of 10 min, a (Fe, Ni) Ti layer of approximately 1.8 m m is formed on the YAG side. Originality/value - Wetting and spreading behavior of the brazing fi ller alloy under different conditions and the influence of the holding time on the interface microstructure of the joint were studied to provide references for obtaining high-quality brazed joints.

201 Stainless steel and 5052 aluminium alloy were laser lap welded, both with and without a Ni foil interlayer. The Ni addition enhanced the metallurgical reaction between molten stainless steel/aluminium, resulting in the formation of the Al0.9Ni1.1 intermetallic compound. First-principles calculations estimated the equilibrium lattice and properties of IMCs (intermetallic compounds). A structural model of the interface revealed that the bonding strengths of Al/IMC and Fe/IMC interfaces surpassed those of IMC/IMC interfaces, making cracks prone to initiate and expand at the latter. Joints without Ni reached a max tensile shear strength of 74.5 N/mm, while those with Ni increased significantly to 101.8 N/mm, marking a substantial 36.6% enhancement.

A Q345 steel butt-welded joint was manufactured using laser-arc hybrid welding (LAHW) technology, and its microstructure, microhardness, and residual stress (RS) distribution were measured. Using ABAQUS software, a sequentially coupled thermo-metallurgical-mechanical finite element method was employed to model the welding RS distribution in the LAHW joint made of Q345 steel. The effects of solid-state phase transformation (SSPT) and transverse restraint on the welding RS distribution were explored. The results show that a large number of martensite phase transformations occurred in the fusion zone and heat-affected zone of the LAHW joint. Furthermore, the SSPT had a significant effect on the magnitude and distribution of RS in the LAHW joint made of Q345 steel, which must be taken into account in numerical simulations. Transverse restraints markedly increased the transverse RS on the upper surface, with a comparatively minor impact on the longitudinal RS distribution. After the transverse restraint was released, both the longitudinal and transverse RS distributions in the LAHW joint reverted to a level akin to that of the welded joint under free conditions.

The diffusion kinetics and mechanisms of Ag/Ti diffusion couple were investigated through experiments and molecular dynamics simulations. The influence of processing parameters, such as temperature (700 degrees C to 850 degrees C) and holding time (15 min to 60 min), on microstructure and phase formation at the Ag/Ti joint was studied. In addition, the mechanical properties of the joints were evaluated. IMCs including AgTi, Ti2Ag, and the Ti(ss, Ag) solid solution exist at the diffusion interface. The activation energy for the growth of the TiAg phase is 98 kJ/mol. Molecular dynamics simulations show that Ag has a higher diffusion coefficient (5.0x10-5 m2/s) compared to Ti (2.5x10-8 m2/s). Meanwhile, the grains at the TiAg/Ti interface are significantly smaller than those at the TiAg/ Ag side. These results indicate that the diffusion flux of Ag is higher than that of Ti, and the TiAg phase priority is formed at the interface. The grain boundary diffusion is a diffusion control mechanism. The Ti(ss, Ag) solid solution at the interface exhibits the highest nano-hardness and modulus, with values of 4.2 +/- 0.1 GPa and 139.6 +/- 0.6 GPa, respectively. The joint brazed at 750 degrees C for 30 min shows a maximum shear strength of 98 MPa, with fractures primarily occurring at the interface between the Ag and TiAg phases. This study provides insights into the diffusion behavior, phase formation dynamics, and mechanical properties of Ag/Ti diffusion couples, offering implications for the development of advanced materials in various engineering applications.

A high entropy alloy (HEA) coating was applied on Ti-6Al-4 V by electron beam cladding Al7(CoFeNi)86Ti7 HEA powder. The optimal electron beam cladding parameters, determined through orthogonal experimental analysis, were: 64 kV accelerating voltage, 12 mA welding beam current, and 3 s scanning time. Microstructure, phase composition, nano-hardness and wear resistance of the coating prepared using optimal parameters were investigated. The primary phases in the top, middle, and bottom regions of the coating were identified as body-centered cubic (BCC) solid solution with Ti-rich compounds (NiTi, Ti2Ni, and Ti2Co), BCC + Ti0.85Al0.15, and Ti0.85Al0.15, respectively. The coating had an average grain size of 3.9 μm, and the dislocation density of the BCC phase was 1.51 × 1014/m². Due to the presence of compounds, fine grains, and high dislocation density, the coating achieved an average nano-hardness of 8.39 ± 0.29 GPa, approximately 1.8 times higher than that of Ti-6Al-4 V. Additionally, the wear rate of the cladded coating was 22.28 ± 4.56 × 10− 6 mm3/(N·m), representing a 65.5